Integrated passive device for RF power amplifier package

ABSTRACT

The present disclosure relates to a radio frequency (RF) power transistor package. It further relates to a mobile telecommunications base station comprising such an RF power transistor package, and to an integrated passive die suitable for use in an RF power amplifier package. In example embodiments, an in-package impedance network is used that is connected to an output of the RF power transistor arranged inside the package. This network comprises a first inductive element having a first and second terminal, the first terminal being electrically connected to the output of the RF transistor, a resonance unit electrically connected to the second terminal of the first inductive element, and a second capacitive element electrically connected in between the resonance unit and ground, where the first capacitive element is arranged in series with the second capacitive element.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of and claims priority to U.S.patent application Ser. No. 15/655,582, filed on Jul. 20, 2017, which ishereby incorporated by reference in its entirety. U.S. patentapplication Ser. No. 15/655,582 claims priority to Netherlands PatentApplication No. 2017206, filed on Jul. 21, 2016, which is also herebyincorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a radio frequency (RF) power amplifierpackage. It further relates to a mobile telecommunications base stationcomprising such an RF power amplifier package, and to an integratedpassive die suitable for such an RF power amplifier package.

BACKGROUND

RF power amplifier packages may comprise a package and a semiconductordie, and the die may be arranged inside the package and provided with anRF power transistor. The RF power transistor may have an outputcapacitance and may be configured to amplify signals at an operationalfrequency. An impedance network may be arranged inside the package forproviding impedance matching and/or filtering. These packages may beused in base stations for the mobile communications market.

The evolution of the mobile communications market is essentially drivenby a continuously increasing amount of data and transmission speed,resulting in a need for an increasingly larger instantaneous signalbandwidth. To linearly amplify wide band signals and minimize the memoryeffects, it may be useful to terminate the second order intermodulationdistortion (IMD) products occurring at relatively low frequencies withvery low impedances. If the impedance seen by an RF power transistor atthese frequencies is too high, the amplitude of the undesired signalcomponents may increase, and the biasing of the transistor may beaffected by feedback of the low-frequency IMD products into the biasingcircuitry.

Another aspect of RF power amplifiers is the ability to deliver theoutput signal at the desired power level. To that end, it may be usefulfor the RF power transistor to be appropriately impedance matched. Inparticular, the effective load seen by the RF power transistor shouldonly have a small reactive part. In practice however, most RF powertransistors may have a considerable output capacitance. As an example, alaterally diffused metal-oxide-semiconductor (LDMOS) transistor,configured to provide output powers in the range of 150 Watts, may havea drain-source capacitance of approximately 50 pF. In the frequency bandof interest, which in the mobile base station market ranges from 600 MHzto 3.5 GHz and more, this capacitance strongly influences the impedanceseen at the drain of the LDMOS.

SUMMARY OF THE DISCLOSURE

FIG. 1A illustrates a circuit topology that addresses the abovementionedinfluence of the output capacitance. This capacitance is denoted by Cdsand is present between the drain (d) and source (s) of the FET. In FIG.1A, a series resonance circuit formed by L1 and C1 is connected to thedrain of the FET. Zload models the load that is presented to the FET,and Lfeed models the feed inductance of the biasing circuit.

Due to its relatively large capacitance value, C1 may be configured toact as a ground for signals at the RF operational frequency of the FET.L1 may be chosen such that it will resonate with Cds at or close to theoperational frequency. This may allow the reactive part of the impedanceseen by the FET to be sufficiently small at the operational frequency.However, at the same time, C1 may resonate with the feed inductanceLfeed of the biasing circuitry at low frequencies. This may introduce apeak in the impedance seen at the drain of the FET, as illustrated inFIG. 1B.

To mitigate this problem, a different topology may be used, which isillustrated in FIG. 2A. This topology differs from the topology in FIG.1A in that a further inductance L2 and a further capacitance C2 havebeen included. C2 has a terminal electrically connected to L2 andanother terminal electrically connected to ground.

Similar to FIG. 1A, C2 may be very large, even substantially larger thanC1, and may act as a ground at RF and lower frequencies. For simplicity,the same component values for L1, Cds, and C1 may be used in thetopologies in FIGS. 1A and 2A.

Similar to FIG. 1B, the circuit in FIG. 2A may show a first resonanceoccurring at a relatively low first resonance frequency related to theresonance between C2 and Lfeed, albeit at a lower frequency due to theinfluence of L2 and C1. However, a second resonance may occur at anintermediate second resonance frequency related to the resonance of L2and C1. L2 and C1 form a parallel resonance circuit that will display atransition between a high positive and high negative reactive part nearthe resonance frequency of L2 and C1. This reactive part will producethe second resonance shown in FIG. 2B.

As can be seen by comparing FIG. 1B and FIG. 2B, the first resonancefrequency may be shifted to lower frequencies. This, in combination withthe second resonance frequency, may allow a better control of theimpedance at the frequencies that are associated with the second ordermodulation.

To further improve the abovementioned impedance behavior, damping can beintroduced. For example, a damping resistor can be placed in series withL2. This resistance may dampen the resonance at the first and secondresonance frequencies. At the operational frequency, the combination ofL2 and C1 may inhibit RF signals from being dissipated in theresistance, such that the impact of the resistance at the operationalfrequency may be minimal.

A practical implementation of C2 will include some energy losses. Thequality factor of a parallel resonance circuit may generally decreasewhen its capacitance is increased. This may, in turn, reduce the peakheight of the impedance at the first resonance frequency. Hence, toreduce the IMD products, C2 may be chosen to be as large as possible.

The first capacitance C1 may also be arranged inside the package. Asthis capacitance may have a non-negligible influence on the RF behavior,it may be desirable for the losses of this capacitor to also beminimized.

The available space inside the package may be limited. Consequently,increasing C2 may result in less space being available for C1. This maybe particularly true when C1 and C2 are integrated on the same die. Forinstance, a highly doped substrate of the die may form one of theelectrodes, and the electrode may be connected to the flange of thepackage that acts as ground. Hence, when C2 is increased, less space maybe available for grounding C1, which in turn may increase its losses.Therefore, in some approaches, a trade off may be found betweenincreasing control of the impedance at the second-order IMD frequenciesand the overall efficiency of the power amplifier.

Embodiments of the present disclosure may provide a circuit topology inwhich the abovementioned trade-off can be improved.

This may be achieved using the topology as claimed in claim 1, which ischaracterized in that the second terminal of the first capacitiveelement is electrically connected to the second capacitive element. Forexample, the second capacitive element may have a second terminalconnected to ground and a first terminal connected to the secondterminal of the first capacitive element and to a second terminal of thesecond inductor. Contrary to the topology of FIG. 2A, the firstcapacitive element is not directly connected to ground but is connectedto the second capacitive element.

As the capacitance of the second capacitive element may be much largerthan the capacitance of the first capacitive element, the secondcapacitive element may have larger electrodes. Furthermore, the secondcapacitive element may act as a ground at those frequencies for whichthe losses of the first capacitive element are relevant. By arrangingthe first capacitive element in series with the second capacitiveelement, the first capacitive element can use the relatively largeelectrode of the second capacitive element as an efficient groundconnection, thereby avoiding the increased resistance observed in otherapproaches where the capacitance of the second capacitive element isincreased at the expense of the grounding of the first capacitiveelement.

The first inductive element can be configured to resonate with theoutput capacitance at or close to the operational frequency.Furthermore, the RF power transistor can be configured to be fed using afeed inductance, and the second capacitive element can be configured toresonate with the feed inductance at a first resonance frequency that issubstantially smaller than the operational frequency. The secondinductive element can be configured to resonate with the firstcapacitive element at a second resonance frequency. Here, the firstresonance frequency may be substantially smaller than the secondresonance frequency, and the second resonance frequency may besubstantially smaller than the operational frequency.

The various resonance frequencies mentioned above may differ, to a smallextent, from the resonance frequencies associated with the impedanceseen at the output of the RF power transistor. For example, theimpedance seen at the output of the RF power transistor may comprise aparallel contribution of the output capacitance, the impedance ofimpedance network, and the impedance associated with a matching networkconnected to the RF power transistor. A resonance in the overallimpedance seen at the output of the RF power transistor can be achievedwhen the impedance of the impedance network forms an open together withthe other impedance contributions. As the impedance of the impedancenetwork near a parallel resonance frequency varies strongly between alarge positive value and a large negative value, such a match can befound for a frequency close to the parallel resonance frequency.

The first and/or second inductive element may comprise an integratedinductor and/or a bond wire. An integrated inductor may comprise aspiral conductor and/or a transmission line realized on a substrate,such as a semiconductor die. This die may correspond to the die on whichthe RF power transistor is located. Alternatively, a separate die may beused on which at least one or all of the abovementioned inductive andcapacitive elements are integrated.

The resonance circuit may comprise a resistive element for damping thefirst and second resonances. This resistive element may be arranged inseries with the second inductive element or can be integrated therewith.By appropriately choosing the inductance and capacitance values, the RFperformance at the operational frequency may be unaffected or hardlyaffected by this resistive element.

The first and/or second capacitive element may comprise an integratedcapacitor. Such a capacitor may be realized on a substrate, such as thefirst semiconductor die. Alternatively, the first and second capacitiveelements may be integrated on a second die, such as a semiconductor die,and the second die may also be arranged inside the package. The packagemay comprise a flange and an output lead, wherein the first and/orsecond die is mounted to the flange, perhaps using a die-bondingtechnique.

When the package is mounted in a final product, such as on a printedcircuit board of a base station amplifier, the flange may be connectedto ground. By connecting the dies on the flange, a ground connection canbe obtained. In some cases, the first and/or second die may comprise ahighly doped substrate allowing a low resistance path through thesubstrate. Alternatively, vias that extend through the substrate may beused to achieve a ground connection between the upper region of the diesand the bottom region that is connected, in a low-ohmic manner, to theflange.

Examples of integrated capacitors include interdigitated capacitors,fringe capacitors, deep trench capacitors, and metal-insulator-metalcapacitors, although the present disclosure does not exclude other typesof capacitors. In an example embodiment, the second capacitive elementmay comprise a deep trench capacitor, and the first capacitive elementmay comprise a metal-insulator-metal capacitor.

The first capacitive element may comprise a first and a second electrodehaving a first dielectric arranged therebetween. Furthermore, the secondcapacitive element may comprise a first and a second electrode having asecond dielectric arranged therebetween, wherein the first electrode ofthe first capacitive element is electrically connected to the firstinductive element, and wherein the second electrode of the firstcapacitive element is electrically connected to the first electrode ofthe second capacitive element. Here, the second electrode of the secondcapacitive element can be electrically connected to ground. As thesecond capacitive element may be substantially larger than the firstcapacitive element, in such a manner that at the operational frequencythe second capacitive element acts as ground, the first capacitiveelement can use the relatively large first electrode of the secondcapacitive element as an efficient ground plane.

The first and second dies may be elongated in a first direction, whereinthe deep trench capacitor may comprise a plurality of trenches extendingin the first die, the second dielectric may be arranged inside thetrenches, a top electrode may be arranged over the second dielectric,and a metal contact layer may be arranged on the top electrode, andwherein the metal contact layer may comprise a plurality of slots alongthe first direction. The second capacitive element may extend a firstdistance in the first direction, and the slots may extend along a seconddistance in the first direction, wherein the second distance may besubstantially equal to the first distance.

When using a second die, which may be generally located in between thefirst die and the output lead of the package, return currents may flowthrough the relatively thin metal contact layer of the deep trenchcapacitor instead of the flange of the package or the semiconductorsubstrate. Such current may introduce losses that deteriorate RFperformance. By arranging slots that extend in a direction perpendicularto the direction of the RF return current, the RF current can be forcedto flow through the flange, which may present a much smaller resistanceto the RF return current.

As described above, a resistive element can be used in the resonanceunit to dampen the first and second resonances. This resistive elementmay be integrated on the second die, for example, in the form of a thinfilm resistor.

The first semiconductor die may comprise an output bond pad assembly,which may be bar-shaped, that is electrically connected to the output.Furthermore, the second die may comprise a first bond pad assembly thatis electrically connected to the first capacitive element, and the RFpower amplifier package may comprise a first plurality of bond wiresthat electrically connect the output bond pad assembly to the first bondpad assembly. In this case, the first plurality of bond wires maysubstantially form the first inductive element, although the presentdisclosure does not exclude embodiments in which these bond wirescooperate with an integrated inductor, arranged on the first and/orsecond die, to form the first inductive element.

The RF power amplifier package may comprise a second plurality of bondwires that electrically connect the output bond pad assembly to theoutput lead. Here, the second plurality of bond wires may form a seriesinductance between the output of the RF power transistor and the outputlead. This inductance may be part of an impedance matching network thatis at least partially arranged inside the package. It may also be usedas part of an impedance inverter for an integrated Doherty amplifier. Insuch a case, the RF power amplifier package may comprise at least oneother RF power transistor. The plurality of RF power transistors may bebiased differently, such that one transistor acts as a main amplifyingstage and the other transistor(s) as a peak amplifying stage. Dependingon the topology used, the second plurality of bond wires may be used toconnect the main or peak amplifying stage to the output lead. It will beunderstood that other arrangements of Doherty amplifiers that include atleast a portion of the impedance inverters and/or signal combinerslocated inside the package are possible and contemplated herein.

The RF power amplifier package may further comprise a third inductiveelement and a third capacitive element arranged in series between theoutput lead and one of the flange, the second die, and/or the secondcapacitive element. This series combination can be used to performin-package matching. The third capacitive element may in these cases, atleast at the operational frequency, be effectively electricallyconnected to ground. The flange or the second capacitive element can beused for this purpose. Alternatively, if the second die comprises ahighly doped substrate, an electrical connection between the secondcapacitive element and this substrate could be realized to achieve theground connection.

The third capacitive element may be integrated on the second die, andthe second die may further comprise a second bond pad assemblyelectrically connected to a terminal of the third capacitive element. Inthis case, the RF power amplifier package may further comprise a thirdplurality of bond wires extending from the second bond pad assembly tothe output lead. This third plurality of bond wires may at leastpartially form the third inductive element. Again, the bond wires may becombined with integrated inductors arranged on the second die. The otherterminal of the third capacitive element can be electrically connectedto one of the flange, the second die, and the second capacitive element.

Alternatively, the second die may comprise a second bond pad assembly,and an integrated third capacitive element having one terminalelectrically connected to the second bond pad assembly and anotherterminal to one of the flange, the second die, and the second capacitiveelement. The RF power amplifier package may comprise a third pluralityof bond wires electrically connecting the second bond pad assembly tothe output lead. The RF power amplifier package may further comprise asecond plurality of bond wires electrically connecting the second bondpad assembly and the output bond pad assembly.

The third inductive element and the third capacitive element may beconfigured for providing an impedance match at the operationalfrequency. The third capacitive element may comprise a deep trench or ametal-insulator-metal capacitor.

The package may further comprise a bias lead and a fourth plurality ofbond wires extending from the bias lead to the first bond pad assembly.This may eliminate the need for Lfeed and may provide significant spacereduction on the external printed circuit board.

The first resonance frequency may lie in the range of 5 MHz to 20 MHz,the second resonance frequency in the range of 300 MHz to 650 MHz, andthe operational frequency in the range of 800 MHz to 3.5 GHz and above.

The first semiconductor die may comprise a Silicon die or a suitablesubstrate, such as Silicon, Silicon Carbide, or Sapphire, having GalliumNitride grown epitaxially thereon. The RF power transistor may compriseat least one of a laterally diffused metal-oxide-semiconductortransistor or a field-effect transistor.

According to a further aspect, the disclosure further provides anintegrated passive die that is suitable for an RF power amplifierpackage as above, wherein the integrated passive die comprises thesecond die as described above.

According to an even further aspect, the disclosure provides a mobiletelecommunications base station comprising the RF power amplifierpackage as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a circuit topology for an RF power amplifier,according to an example embodiment.

FIG. 1B illustrates an impedance as a function of frequency of thecircuit topology depicted in FIG. 1A, according to an exampleembodiment.

FIG. 2A illustrates a circuit topology for an RF power amplifier,according to an example embodiment.

FIG. 2B illustrates an impedance as a function of frequency of thecircuit topology depicted in FIG. 2A, according to an exampleembodiment.

FIG. 3A illustrates a circuit topology for an RF power amplifier,according to an example embodiment.

FIG. 3B illustrates an impedance as a function of frequency of thecircuit topology depicted in FIG. 3A, according to an exampleembodiment.

FIG. 4A illustrates a circuit topology for an RF power amplifier,according to an example embodiment.

FIG. 4B illustrates a circuit topology for an RF power amplifier,according to an example embodiment.

FIG. 4C illustrates a circuit topology for an RF power amplifier,according to an example embodiment.

FIG. 4D illustrates a circuit topology for an RF power amplifier,according to an example embodiment.

FIG. 5A illustrates a circuit topology for an RF power amplifier,according to an example embodiment

FIG. 5B illustrates an arrangement of an RF power amplifier package,according to an example embodiment.

FIG. 6A illustrates a semiconductor die for use in the RF poweramplifier package depicted in FIG. 5B, according to an exampleembodiment.

FIG. 6B illustrates a semiconductor die for use in the RF poweramplifier package depicted in FIG. 5B, according to an exampleembodiment.

DETAILED DESCRIPTION

FIG. 3A illustrates a general topology in accordance with the presentdisclosure. When comparing this topology with the topology in FIG. 2A,it can be seen that C1 is no longer directly connected to ground but isinstead connected to C2. This latter capacitor, being substantiallylarger than C1, may act as a ground at the operational frequency of theRF power transistor. In addition, a resistive element R is arranged inseries with L2.

Similar to the topology of FIG. 2A, a first resonance can be observed inthe impedance seen looking away from the FET illustrated in FIG. 3B,which can be attributed to the parallel resonance of C2 and Lfeed. Atthis resonance frequency, the impedance of the series connection of L2and R may be substantially smaller than the impedance of C1. As such,the effective capacitance that is arranged in parallel to Lfeed may beroughly equal to C2. Moreover, the currents at this frequency may flowthrough R, causing damping of the resonance peak in the impedance.

A second resonance peak can be observed in FIG. 3B, which can beattributed to the parallel resonance of C1 and L2, similar to theresonance in the topology of FIG. 2A. Also, in this case, current mayflow through R, causing damping of the resonance peak in the impedance.

At the operational frequency, L2 may substantially block the RF current,causing the larger part thereof to flow through C1 and C2. Consequently,the impact of the ohmic losses in R may be negligible at thesefrequencies. Moreover, at these frequencies, the effective capacitanceto ground of the resonance unit may be substantially equal to C1, as C1and C2 are arranged in series. L1 and C1 may be chosen such that, at orclose the operational frequency, the resonance circuit acts as aninductance having a value substantially equal to L1. This effectiveinductance may resonate with Cds to mitigate the impact of Cds at theoperational frequency. At this frequency, the RF power transistor maysee only the desired impedance realized by the combination of thematching network, which is at least partially arranged outside thepackage, and the external load.

The description above provides a description of the functionality of thecomponents Cds, L1, L2, R, C1, and C2. It is understood that the valuesfor these components may depend on, inter alia, the desired operationalfrequency, the size of the RF power transistor and the type of thistransistor, the desired impedance behavior of the impedance at thesecond order IMD frequencies, and the desired bandwidth of the RF poweramplifier made using the RF power amplifier package. The disclosure istherefore not limited to a particular range of values of thesecomponents.

FIGS. 4A-4D show further topologies in accordance with the presentdisclosure. Here, an additional capacitor C4 can be identified thatmodels the parasitic capacitance seen at the output lead of the package.Moreover, component C3 and L3 are added to perform an impedance matchinginside the package at the operational frequency, for example to performa downward impedance transformation for transforming the impedance atthe output lead when looking at the external load to a lower value seenby the RF power transistor.

FIGS. 4A-4D differ in how C3 and L3 are connected. Depending on thedesired functionality of L3, different implementations can beidentified. For example, if L3 is intended solely for impedancematching, the following matching stages can be identified at theoperational frequency:

For the FIG. 4A and 4B topology, a first stage may comprise a seriesinductance L4 and a shunt capacitance equal to C3, where C4 may be muchsmaller than C3, and C3 may be much smaller than C2.

For the FIG. 4C and 4D topology, a first stage may comprise a seriesinductance L3 and a shunt capacitance equal to C3, and a second stagemay comprise a series inductance L4 and a shunt capacitor equal to C4.

Alternatively, L3 can be part of an impedance inverter, for instancewhen the RF power amplifier package is to be used in a Dohertyamplifier, wherein the RF power amplifier package comprises an RF powertransistor acting as a main amplifying stage and an RF power transistoracting as a peak amplifying stage. Referring to FIG. 4A, for example, anequivalent pi-network can be formed by the resonance network, Cds, L3,C3, and L4. These components may perform a 90 degrees phase shift, ormultiples thereof, at the operational frequency. In such applications,the resonance unit may be designed such that, at the operationalfrequency, a residual capacitance exists to form the first shuntcapacitor of the pi-network for the impedance inverter.

In FIGS. 4A and 4C, C3 is grounded directly. In practicalimplementations, C3 may be realized as a discrete capacitor that ismounted to the flange separately from the first and second dies.Alternatively, C3 may be integrated on the first or second die. In thislatter case, C3 can be connected to the conducting substrate, which, inturn, can be connected to the flange. When C3 is integrated in thesecond die, it can be connected to C2, as illustrated in FIGS. 4B and4D.

FIG. 5A illustrates an embodiment according to the present disclosure,wherein the feed line, modeled by Lfeed, is integrated in the packageand connected to the second die, and more specifically to the firstcapacitor. This may allow for substantial reduction of the total size ofthe power amplifier and ease of use of the RF power transistor.

FIG. 5B illustrates an implementation of the embodiment of FIG. 5A. FIG.5B shows a package comprising a flange 1, an output lead 2, and a biaslead 3. A pair of semiconductor dies 4 are mounted on the flange 1. Onthese semiconductor dies 4, RF power transistors 5 are arranged, whichare only schematically illustrated. In this example, the RF powertransistors 5 are formed as LDMOS transistors arranged on a highly dopedsubstrate.

The gate input of one of the RF transistors 5 is connected to abar-shaped bond pad assembly 6. A plurality of bond wires 7 are used toconnect to the gate of the RF transistor 5.

The drain output of the RF transistor 5 is connected to a bar-shapedbond pad assembly 8. A plurality of bond wires 9, forming L4, connectthe drain output to output lead 2. A second plurality of bond wires 10,forming L1, connect the drain output to a U-shaped bond pad assembly 11that is arranged on a second die 18. This assembly is electricallyconnected to the common point of L2 and C1. A further plurality of bondwires 12, partially forming Lfeed, connects bias lead 3 to bond padassembly 11. Bond wires 12′ relay the bias to the other RF powertransistor 5.

Bond wires 13, forming L3, connect output lead 2 to a bar-shaped bondpad assembly 14 that is electrically connected to a terminal of C3. Theother terminal of C3 is connected to the top electrode of C2 (notillustrated). Bond wires 15, forming L2, connect bond pad assembly 11 toa bond pad 16 that is electrically connected to a thin film resistor Rthat is located at a buried position 17.

Die 18 may comprise a highly doped Silicon substrate on which C2 isdistributed as a deep trench capacitor. The top electrode of C2 isconnected to the bottom electrode of C1. The other electrode of C2 isformed by the highly doped substrate. The top electrode of C1 isconnected to bond pad assembly 11.

The embodiment in FIG. 5B illustrates two separate dies 4, 18 on whichthe various components can be realized. However, the present disclosuredoes not exclude embodiments where only a single die is used on whichboth the active and passive components are integrated.

As can be seen in FIG. 5B, bond wires 9 carry the output current tooutput lead 2 across die 18. A return current may be associated withthis current. This current is schematically illustrated in FIG. 6A. FIG.6A illustrates the flange 1 on which the die 18 is arranged. FIG. 6Aalso shows the top electrode of C2, which, in this example, is formed asa 1 micrometer thick metal layer 19. The resistance associated with themetal layer 19 may be much higher than the resistance associated withflange 1. In some scenarios, unwanted losses may be introduced at theoperational frequency. The embodiment shown in FIG. 6B may address suchscenarios.

As shown in FIG. 6B, to direct the return current, slots 20 can bearranged in the metal layer 19 that extend perpendicular to the flow ofthe return current in FIG. 6A. Generally, C2 may be distributed over theentire die 18, thereby having an elongated structure extending in afirst direction. Slots 20 may be arranged along this first direction andmay extend over substantially the entire length of the metal layer 19.Using slots 20, the return current may be forced to flow through theflange 1, thereby reducing the losses at the operational frequency.

Although the present disclosure has been described using detailedembodiments thereof, it is understood that the present disclosure is notlimited thereto, but that various modifications can be made to theseembodiments without departing from the scope of the disclosure which isdefined by the appended claims.

What is claimed is:
 1. A radio frequency (RF) power amplifier,comprising: a first semiconductor die, wherein the first semiconductordie comprises an RF power transistor that has an output capacitance(Cds) and is configured to amplify signals at an operational frequency;an impedance network comprising: a first inductive element (L1) having afirst terminal and a second terminal, the first terminal beingelectrically connected to an output of the RF transistor; a resonanceunit being electrically connected to the second terminal of L1; and asecond capacitive element (C2) electrically connected in between theresonance unit and a ground terminal; wherein the resonance unitcomprises (i) a second inductive element (L2) electrically connected inbetween C2 and L1 and (ii) a first capacitive element (C1) having afirst terminal and a second terminal, the first terminal of C1 beingelectrically connected to the second terminal of L1; wherein thecapacitance of C2 is larger than the capacitance of C1; wherein thesecond terminal of C1 is electrically connected to C2; wherein L1, C1,and L2 are chosen such that, at or close to the operational frequency:an impedance of L2 causes more RF current to flow through C1 thanthrough L2; and an effective inductance formed by L1, the resonanceunit, and C2 resonates with Cds; wherein the RF power transistor isconfigured to be fed using a feed inductance (Lfeed), and wherein C2 isconfigured to resonate with Lfeed at a first resonance frequency that issmaller than the operational frequency; wherein L2 is configured toresonate with C1 at a second resonance frequency, wherein the firstresonance frequency is smaller than the second resonance frequency andwherein the second resonance frequency is smaller than the operationalfrequency; and wherein the resonance unit comprises a resistive elementfor damping signals oscillating at the first and second resonancefrequencies.
 2. The RF power amplifier of claim 1, wherein at least oneof L1 or L2 comprises an integrated inductor or a bond wire.
 3. The RFpower amplifier of claim 1, wherein the resistive element is arranged inseries with L2 or is integrated therewith.
 4. The RF power amplifier ofclaim 1, wherein at least one of C1 or C2 comprises an integratedcapacitor.
 5. The RF power amplifier of claim 1, wherein: the firstresonance frequency lies in the range of 5 to 20 MHz, the secondresonance frequency lies in the range of 300 to 650 MHz, and theoperational frequency lies in the range of 800 MHz to 3.5 GHz and above;the first semiconductor die comprises a Silicon die or a Gallium Nitridedie; and the RF power transistor comprises at least one of a laterallydiffused metal-oxide-semiconductor transistor or a field-effecttransistor.
 6. The RF power amplifier of claim 1, further comprising: apackage, wherein the first semiconductor die and the impedance networkare arranged in the package.
 7. The RF power amplifier of claim 6,wherein C1 and C2 are integrated on the first semiconductor die, whereinthe package comprises a flange and an output lead, and wherein the firstdie is mounted to the flange.
 8. The RF power amplifier of claim 6,wherein the package further comprises a bias lead and a fourth pluralityof bond wires extending from the bias lead to C1.
 9. The RF poweramplifier of claim 6, wherein C1 comprises a first electrode, a secondelectrode, and a first dielectric arranged between the first and secondelectrodes of C1, wherein C2 comprises a first electrode, a secondelectrode, and a second dielectric arranged between the first and secondelectrodes of C2, wherein the first electrode of C1 is electricallycoupled to L1, wherein the second electrode of C1 is electricallycoupled to the first electrode of C2, and wherein the second electrodeof C2 is electrically connected to the ground terminal.
 10. The RF poweramplifier of claim 9, wherein: C1 and C2 are integrated on a secondsemiconductor die arranged inside the package; the first and secondsemiconductor dies are elongated in a first direction; C2 comprises adeep trench capacitor with a plurality of trenches extending along thesecond semiconductor die, the second dielectric being arranged insidethe plurality of trenches; a top electrode is arranged over the seconddielectric; and a metal contact layer is arranged on the top electrode,wherein the metal contact layer comprises a plurality of slots along thefirst direction.
 11. The RF power amplifier of claim 10, wherein C2extends a first distance in the first direction, wherein the pluralityof slots of the metal contact layer extend along a second distance inthe first direction, and wherein the second distance is substantiallyequal to the first distance.
 12. The RF power amplifier of claim 6,wherein C1 and C2 are integrated on a second semiconductor die arrangedinside the package, wherein the package comprises a flange and an outputlead, and wherein the first and second semiconductor dies are mounted tothe flange.
 13. The RF power amplifier of claim 12, wherein theresistive element is integrated on the second semiconductor die, andwherein the resistive element is a thin film resistor.
 14. The RF poweramplifier of claim 12, wherein the first semiconductor die comprises anoutput bond pad assembly electrically connected to the output of the RFtransistor, wherein the second semiconductor die comprises a first bondpad assembly electrically connected to C1, wherein the RF poweramplifier package further comprises a first plurality of bond wires thatelectrically connect the output bond pad assembly of the firstsemiconductor die to the first bond pad assembly of the secondsemiconductor die, and wherein the first plurality of bond wires form atleast part of L1.
 15. The RF power amplifier of claim 14, furthercomprising a second plurality of bond wires electrically connecting theoutput bond pad assembly of the first semiconductor die to the outputlead of the package.
 16. The RF power amplifier of claim 14, wherein thesecond semiconductor die further comprises: a second bond pad assembly,and an integrated third capacitive element (C3) having a first terminalelectrically connected to the second bond pad assembly and a secondterminal electrically connected to the flange, the second semiconductordie, or C2.
 17. The RF power amplifier of claim 16, further comprising:a third plurality of bond wires electrically connecting the second bondpad assembly of the second semiconductor die to the output lead of thepackage.
 18. The RF power amplifier of claim 17, further comprising athird inductive element (L3) arranged in series between (i) the outputlead of the package and (ii) the flange, the second semiconductor die,or C2, wherein the third plurality of bond wires form at least part ofL3; wherein L3 and C3 are configured to provide an impedance match forthe RF power transistor at the operational frequency, and wherein C3comprises a deep trench capacitor or a metal-insulator-metal capacitor.19. An integrated passive die for use in a radio frequency (RF) poweramplifier comprising: a first semiconductor die, wherein the firstsemiconductor die comprises an RF power transistor that has an outputcapacitance (Cds) and is configured to amplify signals at an operationalfrequency; an impedance network comprising: a first inductive element(L1) having a first terminal and a second terminal, the first terminalbeing electrically connected to an output of the RF transistor; aresonance unit being electrically connected to the second terminal ofL1; and a second capacitive element (C2) electrically connected inbetween the resonance unit and a ground terminal; wherein the resonanceunit comprises (i) a second inductive element (L2) electricallyconnected in between C2 and L1 and (ii) a first capacitive element (C1)having a first terminal and a second terminal, the first terminal of C1being electrically connected to the second terminal of L1; wherein thecapacitance of C2 is larger than the capacitance of C1; wherein thesecond terminal of C1 is electrically connected to C2; wherein L1, C1,and L2 are chosen such that, at or close to the operational frequency,:an impedance of L2 causes more RF current to flow through C1 thanthrough L2; and an effective inductance formed by L1, the resonanceunit, and C2 resonates with Cds; wherein the RF power transistor isconfigured to be fed using a feed inductance (Lfeed), and wherein C2 isconfigured to resonate with Lfeed at a first resonance frequency that issmaller than the operational frequency; wherein L2 is configured toresonate with C1 at a second resonance frequency, wherein the firstresonance frequency is smaller than the second resonance frequency andwherein the second resonance frequency is smaller than the operationalfrequency; and wherein the resonance unit comprises a resistive elementfor damping signals oscillating at the first and second resonancefrequencies.
 20. A mobile telecommunications base station comprising aradio frequency (RF) power amplifier, wherein the RF power amplifier ofthe mobile telecommunications base station comprises: a firstsemiconductor die, wherein the first semiconductor die comprises an RFpower transistor that has an output capacitance (Cds) and is configuredto amplify signals at an operational frequency; an impedance networkcomprising: a first inductive element (L1) having a first terminal and asecond terminal, the first terminal being electrically connected to anoutput of the RF transistor; a resonance unit being electricallyconnected to the second terminal of L1; and a second capacitive element(C2) electrically connected in between the resonance unit and a groundterminal; wherein the resonance unit comprises (i) a second inductiveelement (L2) electrically connected in between C2 and L1 and (ii) afirst capacitive element (C1) having a first terminal and a secondterminal, the first terminal of C1 being electrically connected to thesecond terminal of L1; wherein the capacitance of C2 is larger than thecapacitance of C1; wherein the second terminal of C1 is electricallyconnected to C2; wherein L1, C1, and L2 are chosen such that, at orclose to the operational frequency,: an impedance of L2 causes more RFcurrent to flow through C1 than through L2; and an effective inductanceformed by L1, the resonance unit, and C2 resonates with Cds; wherein theRF power transistor is configured to be fed using a feed inductance(Lfeed), and wherein C2 is configured to resonate with Lfeed at a firstresonance frequency that is smaller than the operational frequency;wherein L2 is configured to resonate with C1 at a second resonancefrequency, wherein the first resonance frequency is smaller than thesecond resonance frequency and wherein the second resonance frequency issmaller than the operational frequency; and wherein the resonance unitcomprises a resistive element for damping signals oscillating at thefirst and second resonance frequencies.